Apparently, the tree can be seen from Kaesong, North Korea, which is miles from the border and the demilitarized zone. The tree (which is actually not a tree at all and more of a bunch of lights in the shape of one) had recently stayed dim as part of an agreement to minimize propaganda efforts from both sides. But now with the lights on, South Korea fears that the North could fire upon it, so it has surrounded the tree with marines.